THE GIFT OF THE GAB

How Do you judge intelligence at first blush? Is it how someone looks, what their job is, what they say, how they say it? Are you intelligent if you can multiply 203 by 47 in your head, or hold the floor with a speech? Are you dumb if you can't load a new computer programme or speak a foreign language?

First impressions of intelligence are based on many things. Some have foundation - people with myopia are more likely to have high IQ scores, for example. Some don't. Despite the cliche of "dumb blondes", we are far more likely to assume attractive people's assets run to high intelligence than those who are less good-looking. And if you're very good at one thing, there tends to be a "halo" effect over everything, at least until you prove otherwise.

Something the Western world definitely sees as sure-fire proof of brain power is fluid, eloquent, expressive speech. So many of our social interactions rely on verbal exchanges, negotiations and reasoning and - businessman or busker, politician or postman - if you can talk the good talk, people will think you are more intelligent than those who hum and haw and strangulate their sentences.

"We rate verbal ability rather highly in the intelligence stakes. We're inclined to judge people who talk fast as more intelligent and indeed verbal fluency does usually correlate with IQ," says Nicholas Mackintosh, professor of experimental psychology at Cambridge University. "While we acknowledge people who are expert in practical tasks, we tend to discount this as a measure of intelligence and think they've just learnt how to do it. But we're less ready to say that when people are good at talking."

If words, as Samuel Johnson said, are the "dress" of rational thought, a good vocabulary is the Wonderbra of intellect. So imagine meeting Nikki, a teenager who's bubbly and full of colourful conversation about crushes, holidays and life in general, but has a traditional IQ of 69. Or nine- year-old Sam - if you can tear him away from the computer - who will play to the crowd with opinions and jokes, but can't count or tie his laces. Or seven-year-old Freddie who can't tell the time, but can sing all the Spice Girls hits from memory and talk coherently about tyrannosauruses.

All three have Williams syndrome, a genetic learning disability which challenges almost everything we take for granted about the relationship between language and intelligence. Affecting roughly one in 20,000 people, Williams syndrome causes a distinctive pattern of abilities, behaviour and personality characteristics unlike any other learning disability, and a typical IQ rating of between 40 and 70, usually the moderate to severe learning disabled category.

By school age many of these children talk like angels, in flowing, descriptive language, using long words and adult phrases. They employ a rich variety of grammar and can verbally correct ungrammatical sentences twice as quickly as normal children. When asked to tell a story from pictures, they make their voices come alive with drama and sound effects, establishing characters and telling well structured and detailed tales.

When it comes to vocabulary, children with the syndrome often excel. In studies which asked teenagers to name as many animals as they could in a minute, those with Williams syndrome gave as many as normal subjects and included more unusual choices, such as yak, ibex, chihuahua, vulture. In comparison, Down's syndrome teenagers, who have a similar IQ range, named very few and often gave words unrelated to animals.

In addition to language skills, Williams syndrome children are sociable, with great awareness of body language and emotions. They are concerned about people's feelings and like little better than to look after others, run errands, chat and entertain.

Mike Adlam, chairman of the Williams Syndrome Foundation and father of nine-year-old Sam, says his son "has a tremendous humour and loves to make people laugh. He's also got unbelievable emotions which oscillate tremendously - one single note of a tune can reduce him to gales of tears, another to wreaths of smiles. On the computer Sam's `cleverer' than all of us because he's persistent, but counting to 10 doesn't mean a lot and he's as likely to count backwards. Yet he'll remember a spot where we saw a hedgehog five years ago."

The flip side of this sociability is that Williams syndrome people often go beyond the line of acceptability. That they can be over- friendly to friends and strangers alike is a particularly worrying trait for parents and carers.

There is also no doubt of their learning problems. Their spatial, numeracy and co-ordination skills are severely limited. Few can write and most need help with everyday activities such as dressing, setting tables, crossing the street or paying for a bus ticket. But the combination of fluency and outgoingness can suggest that a child or adult is more able than he or she actually is.

Professor Annette Karmiloff-Smith, senior research scientist at the Medical Research Council's Cognitive Development Unit in London who has carried out extensive studies into Williams syndrome puts it this way. "Williams syndrome teenagers and young adults seem to discover that language is their ecological niche, that it's where they excel, and they use it enormously. They get on far better with adults than their peers and they use language to have an impact on the world because they know people listen to them.

"If a child can hardly speak, we send them straight away to special classes. But if a child is very fluent and very engaging and not at all shy, that camouflages their learning problems and teachers tend to think they're just pretending, or that they're lazy or naughty, instead of realising that they have a real cognitive deficit."

In Britain, says Karmiloff-Smith, language is a carrier of social class and intelligence. "If you've got a child with an IQ of 50 who sounds very elegant and uses long words, it questions what we mean by intelligence. One of the reasons that language is thought of as a vehicle for intelligence is because we are the only species that appears to have a complex grammar. We have to rethink what our concept of intelligence is."

The interplay between linguistic and learning ability in Williams syndrome presents a huge challenge to investigators of cognitive development. Many believe it presents an unparalleled opportunity to probe the deepest mysteries of the human brain. While science has long thought that sophisticated language needed to piggyback on a certain level of intellect to develop, Williams syndrome, with its exotic patterns of learning and development blows this apart and begs questions such as, are there special "language" genes, or even genes for sociability?

There are, as yet, no defini- tive answers to these complex questions, but there are tantalising smoke signals.

First the neurobiology. While Both Williams syndrome and Down's syndrome brains are about 80 per cent of normal size, researchers have found no obvious differences in the cerebral cortex (the folded surface layer of the brain responsible for "thinking" functions such as memory, understanding, decision-making) to explain the Williams syndrome islands of ability. They have, however, found three puzzling differences.

The cerebellum, located at the back of the skull and responsible mostly for co-ordinating voluntary movement, is significantly larger in Williams syndrome than in Down's syndrome, and even slightly larger than in normal brains. So too is the prefrontal cortex, which is thought to control things such as personality, anticipation of events and sense of conscience. Lastly, Williams syndrome brains are packed with neurones, the excitable cells of the nerve system, with clusters in unusual spots.

No one knows quite what all this means, but some suggestions are exciting scientists, including the possibility that these changes and their intellectual consequences might be influenced genetically. The genetic cause of Williams syndrome was pinned down two years ago to a small missing chunk of DNA on Chromosome 7. This deletion includes the gene that codes for elastin, a protein which manages tissue elasticity and whose absence results, among other things, in a heart defect called supra-valvular aortic stenosis (SVAS) - a thickening of the artery walls which all Williams syndrome people have. In severe cases, SVAS requires treatment and is primarily important as a diagnostic tool for the syndrome.

While the discovery of elastin - or the lack of it - doesn't explain all the unusual characteristics of Williams syndrome, the find highlighted the deleted section of DNA and provided geneticists with a scientific treat - the exact location of a genetic defect and a broad and consistent set of behavioural characteristics to match it against.

Dian Donnai, professor of clinical genetics at the University of Manchester and one of the first genetic investigators of the syndrome says: "We know that all the various facets of Williams syndrome must be due to more than just the elastin gene, otherwise everyone with SVAS would have Williams syndrome. Elastin is one currant in a slice of currant cake and there are now various groups trying to find the other `currants' that might explain some of the other facets of the syndrome.

"We are all looking for patients with bits of Chromosome 7 missing because if we can compare those with smaller and larger deletions, we will be able to work out what's different," says Donnai. Late last year, a research group from Salt Lake City, Utah, announced they'd already found the first "thinking" gene through this process. Reporting in the respected biological journal Cell, they linked a protein called LIM kinase to the cognitive profile of Williams syndrome. But the finding is controversial, says Donnai, and the race for the thinking genes still on.

Geneticists aren't the only ones making careful comparisons; cognitive scientists hope the puzzles of Williams syndrome may cast light on the intricate processes of normal brains where linguistic and non-linguistic cognitive functions are so intimately intertwined as to be almost impossible to study separately.

Karmiloff-Smith is working on a hypothesis that Williams syndrome people use more parts of their brain for language processing than normal. In a normal baby, she says, the cerebral cortex develops a huge number of connections. With time, some are pruned and the remainder specialise into different functions, such as speaking, hearing, tasting, touching. In Williams syndrome this specialisation does not seem to occur in the same way and it appears that more of the brain may be taken up with language processing and memory, possibly in the same way that in blind people, areas of the brain previously given over to processing sight can be "invaded" by connections processing sound and touch.

As language is handled by the brain's left hemisphere and spatial abilities by the right, one might conclude that Williams syndrome is purely a right hemisphere disorder. But, says Karmiloff-Smith, its characteristics contradict that. For example, Williams syndrome people are as good as normal people at recognising faces, typically a function of the right hemisphere. But they do it differently, by picking up on details such as the shape of lips or expressions rather than taking a global view.

While science ponders the meaning of their unique abilities, for those with the syndrome and their families the main concern is how to use them to best advantage. Mike Adlam is deliberately fostering Sam's computer obsession and is amazed at the learning he sees. "Sam can take a new programme and load it. He knows he's got to find files with specific suffixes on them, and he can do it. The computer is a great leveller and in the future Sam may be able to find a niche. There's an amazing amount of intellect to be got out of him. The problem is how."

Karmiloff-Smith is less sure that such a key can be found. But, she says, early diagnosis and "massive" training in number, attention and spatial skills could enhance compensatory strategies and help Williams syndrome people function better in the world. Interesting-ly, she says, training could also include learning foreign languages.

"Instead of putting them into special schools where they learn manual tasks with which they have real difficulties, they should go to schools where they are taught several languages. They couldn't interpret at conference level, but properly supervised they could, for example, welcome people to a fast-food restaurant in each of their own languages and take orders and pass them on in English." Karmiloff-Smith adds that she pitched just such a pilot proposal to McDonald's, but was turned down flat. "It's a great shame. This is just the kind of work that would make Williams syndrome people feel good because they'd be doing exactly what they're good at - talking to people and passing on linguistic messages."

The classic clinical and behavioural signs of Williams syndrome were fully described in 1987 but, says Dr Orlee Udwin, consultant clinical psychologist at Lambeth Healthcare and part of the team that spelled out the full exotic profile, many doctors remain unaware of the condition and families often endure months, even years, of anxiety before diagnosis.

GP Dr Mike Wolfman and his wife Fran, whose seven-year-old son Freddie has Williams Syndrome, spent nine months trying to persuade paediatricians that they were not "over- anxious professional parents", while Carol Mathurin, who has a filing cabinet of background information on her daughter Nikki's condition, spent nine years trying persuade consultants and authorities that she was not a neurotic mother.

Short attention span, highly distractable but also subject to all-engrossing obsessions.

Over-friendly and tactile and lacking recognition of social boundaries.

For all this catalogue of difficulties, the one word consistently used by family, carers and clinicians to describe Williams syndrome people is "charming". As Nikki Mathurin says: "People who know me like me for who I am not what I am, they like me for my personality. I think people think of me as a hard worker who does well on my courses, and as a very bouncy person who's very friendly and easy going to be with."